diff --git a/modules/mail.nix b/modules/mail.nix
index d5be613..d5c3ebf 100644
--- a/modules/mail.nix
+++ b/modules/mail.nix
@@ -71,6 +71,8 @@ in
       '';
       config = {
         home_mailbox = "Maildir/";
+        # hostname used in helo command. It is recommended to have this match the reverse dns entry
+        smtp_helo_name = "x8d1e1ea9.agdsn.tu-dresden.de";
         smtp_use_tls = true;
         # smtp_tls_security_level = "encrypt";
         smtpd_use_tls = true;